Plastic packaged semiconductor devices have an cost advantage over hermetic, ceramic packaged semiconductors. The plastic in plastic packages have the disadvantage that moisture absorbed into the package can lead to reliability failures. Failures result from corrosion on the silicon chip, the gold wire connections which are connected to the silicon chip, and on the supporting structure such as the lead frame. As miniaturization components continues, the trend is for thinner and thinner plastic packages. This increases the possibility of moisture absorption into the plastic package.